Trees monoecious, to 35 m tall, not suckering from roots. Trunk straight, to 70 cm d.b.h.; crown conical; bark scaly, adaxially red-brown on old trees. Ultimate branchlets usually pendu-
lous, grayish green, 10-27 cm × 0.8-0.9 mm; articles (2.5-)4-9 mm. Leaves erect and appressed to branchlets, (6 or)7(or 8) per whorl, lanceolate or triangular, 1-3 mm. Male inflorescences 1-4 cm. Cones ellipsoid, 1.2-2.5 cm, grayish green or yellowish brown tomentose when young, glabrous at maturity, base and apex truncate to obtuse; apex of bracteoles slightly obtuse or acute. Samaras 5-8 mm including wing. Fl. Apr-May, fr. Jul-Oct. 2n = 18, 20*.
Because of its nitrogen-fixing capability, sheoak can colonize nutrient-poor soils . It can grow in sloughs, sawgrass (Cladium jamaicensis) glades, wet prairies, saltmarshes, pinelands, along rocky coasts, on sandbars, dunes, and islands, and in water-logged clay or brackish tidal areas [3,10,14,17,18]. C. equisetifolia is found only in south Florida because of its cold intolerance. It is resistant to salt spray but not to prolonged flooding. C. cunninghaminana grows along freshwater streambanks and is not salt tolerant . It is more resistant to cold temperatures than C. equisetifolia . C. glauca grows on steep slopes as well as in intermittently flooded or poorly drained sites. It is salt tolerant .
Some associates of sheoak include eucalyptus (Eucalyptus spp.), melaleuca (Melaleuca quinquenervia), lovegrass (Eragrostis spp.), muhly grasses (Huhlenbergia spp.), beard grasses (Andropogon spp.), plume grass (Erianthus giganteus), saltbush (Baccharis halimifolia), wax myrtle (Myrica cerifera), willow (Salix spp.), sweetbay (Magnolia virginiana), redbay (Persia borbonia), and coco plum (Chrysobalanus icaco) . Native associates in the Northern Mariana Islands include Neisosperma, Barringtonia, Terminalia, Heritiera, Cynometia, and Cordia [5,6].
Sheoak is extremely fast growing, crowding out many native plants and creating sterile environments for both plants and animals . It forms dense roots, which deplete soil moisture and break water and sewer lines. It is also susceptible to windthrow during hurricanes . Cutting often induces sprouting, so it is not an effective control method. Chemicals, such as 2,4,5-T, 2,4-D, or Garlon 3A, can be used to eradicate sheoak [10,14].